The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: Oddities

Who’d’a thunk it?

  • Antique Desk Chair Woodwork

    Antique Desk Chair Woodwork

    A wood desk chair that I’ve known since I was a pup finally got some much-needed attention, although not a restoration. By and large, I’m finally sorting out that corner of the basement and needed to put the chair’s parts back together so I can work on something else.

    The wood seat consists of several slabs glued along keyed joints, one of which had fractured into a rough mess. Amazingly, the two sides fit perfectly together, albeit with the bottom no longer a planar surface, and glued up just like they should:

    Wood desk chair - seat clamping
    Wood desk chair – seat clamping

    The chair isn’t up to contemporary office standards, but it has a seat elevation screw, a backrest with adjustable angle & elevation, and even a backrest tension setting:

    Wood desk chair - ironwork
    Wood desk chair – ironwork

    It was the cutting edge of desk chair technology:

    Wood desk chair - patented
    Wood desk chair – patented

    I vaguely recall it rolled on long-vanished steel-wheeled casters. Somewhat less long ago, one of the legs broke enough to lose its caster socket (about which, more later), so I set about yanking the three remaining sockets:

    Wood desk chair - caster socket removal
    Wood desk chair – caster socket removal

    During that struggle, another leg revealed a neat woodwork joint:

    Wood desk chair - leg joint
    Wood desk chair – leg joint

    It’s easy to remove a caster socket when you can bash it from the top!

    Gluing that piece back in place required Too Many Clamps™ aligning it with the leg:

    Wood desk chair - leg clamping
    Wood desk chair – leg clamping

    But the end result looks pretty good:

    Wood desk chair - leg glued
    Wood desk chair – leg glued

    They did a nice job of matching the wood grain; I hadn’t noticed that joint while attacking the socket.

    Pending restoring the broken leg’s socket, the soon-to-arrive new casters will clash horribly with the chair’s woodwork. At least it’ll roll again and its new plastic wheels won’t scar the floors.

  • Squirrels Need Sleep, Too

    Squirrels Need Sleep, Too

    Spotted outside a window:

    Sleepy Squirrel
    Sleepy Squirrel

    The one on the right stayed in that pose, with eyes getting heavier and heavier, until it nodded off. The other squirrel wasn’t quite that far gone and, after a minute, turned around to see what was(n’t) happening.

    Those two squirrels have been chasing each other around the yard for several weeks, so they’re either siblings or a mated pair.

    I’ve never seen a squirrel take a nap before and it seemed like a good idea for the afternoon …

  • Terms of Use: Do Not Read

    Terms of Use: Do Not Read

    Attempting to use the guest WiFi network requires agreeing to their Terms of Use:

    Guest WiFi signon - poor color choice
    Guest WiFi signon – poor color choice

    While it may be possible to read that, I pretty much gave up.

    While one should never ascribe to malice what can be explained by stupidity, it’s also true that any sufficiently advanced stupidity is indistinguishable from malice.

  • Optional Phreesia Authorization

    Optional Phreesia Authorization

    Our medical practice has been Borged by Optum, which is, through a number of corporate cutout layers, owned by UnitedHealth Group, so (despite claims to the contrary) our doctors effectively work for a health insurance company. No, they may not be paid by UHG, but following the money in reverse shows the flow of influence.

    Apparently this has slightly affected the original practice’s reliance on Phreesia for pre-visit sign-in information collection although, as before, Phreesia still really wants to scatter your precious personal bits to the far corners of the InterWebs:

    Phreesia optional authorization - 2024 version
    Phreesia optional authorization – 2024 version

    The wall o’ text is a bit shorter then the earlier version and cannot be scrolled or printed. It still admits:

    There is the potential for my health information … to be subject to redisclosure and to no longer be protected by the HIPAA Privacy Rule.

    Yes, I understand that’s the whole point of getting me to agree to release my private bits to Phreesia, so they can make money by selling it to the highest bidder(s).

    What’s new is the previous page in the sequence, of which I do not have a screenshot, presumably coming from Optum, emphasizing in bold type that I do not have to authorize Phreesia’s data collection.

    I infer this means two things:

    • Optum / UHG has had their awareness raised about this nonsense
    • Phreesia contractually requires that dark-pattern page

    Yes, I understand that I have no privacy and should get over it, but somehow this sort of behavior rankles …

  • Laser-marked Hole Drilling Spots

    Laser-marked Hole Drilling Spots

    While setting up to drill holes in the aluminum base for the running light buck converter, I wondered if laser-marking the spots directly from the solid model would work better than my usual fumbling around.

    The solid model:

    Running Light - power box - bottom view
    Running Light – power box – bottom view

    Export projections of the pieces from OpenSCAD as an SVG file:

    Running Light - power box - Projection view
    Running Light – power box – Projection view

    Import into LightBurn, set up for a very fast, very light cut and Fire The Laser:

    Laser-marked hole spots - masking tape
    Laser-marked hole spots – masking tape

    That’s in ordinary masking tape on a hard-anodized sheet of aluminum from the pile, which looked better than I expected.

    The same aluminum covered with blue tape:

    Laser-marked hole spots - blue tape - hard anodize
    Laser-marked hole spots – blue tape – hard anodize

    Which looks much better in person than it does in the photo.

    On a soft aluminum sheet from the Basement Warehouse Zone:

    Laser-marked hole spots - blue tape - sheet aluminum
    Laser-marked hole spots – blue tape – sheet aluminum

    The dark outline is a comfort mark hand-drawn around a chipboard test piece to verify the layout fit between random holes drilled in the sheet during its previous life.

    A closer look at a corner hole:

    Laser-marked hole spots - blue tape - hard anodize - detail 1
    Laser-marked hole spots – blue tape – hard anodize – detail 1

    And the center hole:

    Laser-marked hole spots - blue tape - hard anodize - detail 2
    Laser-marked hole spots – blue tape – hard anodize – detail 2

    The holes appeared in the right places after center-punching by eye, but the fragility of those four little tape leaves around the center point must be experienced to be believed.

    And, yes, those are deliberately low-polygon approximations to a circle, because I’m a low-poly kind of guy.

    I really need an optical center punch if I do more such silliness. The box with those HP plotter digitizing sights recently came to hand, so I suppose I should make something.

  • Somebody’s Gotta Go First: Cybertruck

    Somebody’s Gotta Go First: Cybertruck

    Encountered on the way home with a trailer load of groceries:

    Tesla Cybertruck - front - 2024-05-14
    Tesla Cybertruck – front – 2024-05-14

    It’s about as distinctive as (yet much uglier than) Amazon’s Rivian trucks:

    Tesla Cybertruck - rear - 2024-05-14
    Tesla Cybertruck – rear – 2024-05-14

    What I do not understand is the lack of a license plate on that front bumper, here in New York State where front license plates are mandatory. I’ve noticed several Tesla vehicles (in their S3XY automotive series, among which I cannot distinguish) without front plates, so it must be a Tesla owner thing.

    The WordPress AI image for this post gets the angular aspect right, along with the missing plate:

    Tesla Cybertruck - WP AI image
    Tesla Cybertruck – WP AI image

    Cybertruck, fear me!

  • Samsung Microwave Gas Sensor Teardown

    Samsung Microwave Gas Sensor Teardown

    With the microwave back in operation, I thought I might learn something about the failed gas sensor:

    Figaro TGS880 - base
    Figaro TGS880 – base

    Given that much information, finding the datasheet for a Figaro TGS880 sensor didn’t require much effort. In case you were wondering, the replacement sensor has no trace of branding or identification.

    The sensor element has a resistance varying with gas concentration, for a variety of test gases I hope our kitchen never contains in such abundance:

    Figaro TGS-880 Gas Sensor - response plot
    Figaro TGS-880 Gas Sensor – response plot

    The measurement circuit:

    Figaro TGS-880 Gas Sensor - measurement circuit
    Figaro TGS-880 Gas Sensor – measurement circuit

    I betcha the microwave waits for an order-of-magnitude resistance drop from whatever the starting value might be, then calls it done.

    The belly band holding the steel mesh to the plastic base is no match for a Dremel slitting wheel:

    Figaro TGS880 - opening
    Figaro TGS880 – opening

    As the saying goes, Sensoria est omnis divisa in partes tres:

    Figaro TGS880 - teardown
    Figaro TGS880 – teardown

    A closer look at the sensor element:

    Figaro TGS880 - interior
    Figaro TGS880 – interior

    The granular surface does not get along well with the 5× digital zoom required to fill the phone’s sensor, but you get the general idea:

    Figaro TGS880 - element detail
    Figaro TGS880 – element detail

    The heater measured 30 Ω on the dot and the sensor was an open circuit on the 100 MΩ range. Connecting the heater to a 5 V supply dropped the sensor resistance to 800 kΩ @ 50 %RH and a warm breath punched it to about 2 MΩ. That’s with an ohmmeter because I haven’t yet unpacked the Electronics Bench, but seems far above the spec of 20-70 kΩ in air.

    So it’s still a sensor, even if it’s not within spec.

    The WordPress AI-generated image for this post is … SFnal:

    Figaro TGS-880 Gas Sensor - AI generated image
    Figaro TGS-880 Gas Sensor – AI generated image

    My pictures apparently aren’t up to contemporary blog standards …